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4242e224e6
get_random_u32_below returns a random integer in the interval [0, ceil), with uniform distribution. Sponsored by: Serenity CyberSecurity, LLC Reviewed by: emaste MFC after: 1 week (cherry picked from commit 9289c1f6f1514e714b17026c50ec09282f079cba)
120 lines
3 KiB
C
120 lines
3 KiB
C
/*-
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* Copyright (c) 2010 Isilon Systems, Inc.
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* Copyright (c) 2010 iX Systems, Inc.
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* Copyright (c) 2010 Panasas, Inc.
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* Copyright (c) 2013-2016 Mellanox Technologies, Ltd.
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* All rights reserved.
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* Copyright 2023 The FreeBSD Foundation
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*
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* Portions of this software was developed by Björn Zeeb
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* under sponsorship from the FreeBSD Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _LINUXKPI_LINUX_RANDOM_H_
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#define _LINUXKPI_LINUX_RANDOM_H_
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#include <linux/types.h>
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#include <sys/random.h>
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#include <sys/libkern.h>
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static inline void
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get_random_bytes(void *buf, int nbytes)
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{
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arc4random_buf(buf, nbytes);
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}
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static inline u_int
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get_random_int(void)
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{
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u_int val;
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get_random_bytes(&val, sizeof(val));
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return (val);
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}
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#define get_random_u32() get_random_int()
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/*
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* See "Fast Random Integer Generation in an Interval" by Daniel Lemire
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* [https://arxiv.org/pdf/1805.10941.pdf] for implementation insights.
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*/
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static inline uint32_t
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get_random_u32_inclusive(uint32_t floor, uint32_t ceil)
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{
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uint64_t x;
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uint32_t t, v;
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MPASS(ceil >= floor);
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v = get_random_u32();
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t = ceil - floor + 1;
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x = (uint64_t)t * v;
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while (x < t)
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x = (uint64_t)t * get_random_u32();
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v = x >> 32;
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return (floor + v);
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}
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static inline u_long
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get_random_long(void)
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{
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u_long val;
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get_random_bytes(&val, sizeof(val));
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return (val);
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}
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static inline uint64_t
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get_random_u64(void)
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{
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uint64_t val;
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get_random_bytes(&val, sizeof(val));
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return (val);
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}
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static inline uint32_t
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get_random_u32_below(uint32_t max)
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{
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return (arc4random_uniform(max));
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}
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static __inline uint32_t
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prandom_u32(void)
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{
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uint32_t val;
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get_random_bytes(&val, sizeof(val));
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return (val);
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}
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static inline u32
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prandom_u32_max(u32 max)
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{
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return (arc4random_uniform(max));
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}
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#endif /* _LINUXKPI_LINUX_RANDOM_H_ */
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